linux-kernel - [PATCH 40/43] x86/mm/kaiser: Add a function to check for KAISER being enabled

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Date:   Fri, 24 Nov 2017 18:24:08 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...capital.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 40/43] x86/mm/kaiser: Add a function to check for KAISER being enabled

From: Dave Hansen <dave.hansen@...ux.intel.com>

Currently, all of the checks for KAISER are compile-time checks.

Runtime checks are needed for turning it on/off at runtime.

Add a function to do that.

Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: daniel.gruss@...k.tugraz.at
Cc: hughd@...gle.com
Cc: keescook@...gle.com
Cc: linux-mm@...ck.org
Cc: luto@...nel.org
Cc: michael.schwarz@...k.tugraz.at
Cc: moritz.lipp@...k.tugraz.at
Cc: richard.fellner@...dent.tugraz.at
Link: https://lkml.kernel.org/r/20171123003518.B7D81B14@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/kaiser.h | 5 +++++
 include/linux/kaiser.h        | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/arch/x86/include/asm/kaiser.h b/arch/x86/include/asm/kaiser.h
index 040cb096d29d..35f12a8a7071 100644
--- a/arch/x86/include/asm/kaiser.h
+++ b/arch/x86/include/asm/kaiser.h
@@ -56,6 +56,11 @@ extern void kaiser_remove_mapping(unsigned long start, unsigned long size);
  */
 extern void kaiser_init(void);
 
+static inline bool kaiser_active(void)
+{
+	extern int kaiser_enabled;
+	return kaiser_enabled;
+}
 #endif
 
 #endif /* __ASSEMBLY__ */
diff --git a/include/linux/kaiser.h b/include/linux/kaiser.h
index 77db4230a0dd..a3d28d00d555 100644
--- a/include/linux/kaiser.h
+++ b/include/linux/kaiser.h
@@ -28,5 +28,10 @@ static inline int kaiser_add_mapping(unsigned long addr, unsigned long size,
 static inline void kaiser_add_mapping_cpu_entry(int cpu)
 {
 }
+
+static inline bool kaiser_active(void)
+{
+	return 0;
+}
 #endif /* !CONFIG_KAISER */
 #endif /* _INCLUDE_KAISER_H */
-- 
2.14.1